1. Field of the Invention
The present invention relates to a combination gear used in a drive system device of an image forming apparatus and the like, a detachable unit, and an image forming apparatus using these.
2. Description of the Related Art
In image forming apparatuses such as copying machines, printers, facsimile machines, and multi-function machines, generally a coupling and gears are employed as means for transmitting motive power from the image forming apparatus main unit to a detachable unit such as a consumables cartridge of toner or the like or a paper supply cassette.
The coupling connects a main unit-side drive shaft and a driven shaft provided on the cartridge or the detachable unit in an axial direction.
For example, JP 2005-241946A proposes a configuration in which a coupling in which a triangular hole is formed is provided on an image forming unit side and a triangular columnar joint is provided on a main unit side. Drive transmission means based on this coupling have a problem in that a shaft bearing or a spring or the like is required and there are a large number of components.
The gears connect a driving gear on the main unit side and a driven gear provided on the cartridge or the detachable unit from a radial direction. In drive coupling means using gears, since the rotation direction of the gears and the relative position of the driving gear and the driven gear in the mounting direction of the cartridge or detachable unit are limited, the drive system becomes long and the number of components such as gears and caulking shafts increases. Moreover, in order to prevent damage due to impact between the tooth tops of the driving gear and the driven gear when the cartridge or detachable unit is mounted, it is necessary to provide a one-way mechanism in the coupling portion.
In providing the one-way mechanism, a commonly known one-way clutch may be interposed between the driving gear or the driven gear and the shaft thereof such that when the gear rotates in one direction, the rotational force is transmitted to the shaft via the one-way clutch and the shaft rotates integrally, and when the gear rotates in another direction, transmission of the rotational force to the shaft is cut off by the one-way clutch. This involves problems in that costs and the number of components are increased.
In printers, which are the basis of multi-function machines, in order to enablefull front access to ensure excellent operability in which paper restocking, paper jam processing, consumables replacements and the like can be carried out from the front of the apparatus, it is common for the direction in which paper travels from the paper supply cassette to be set to a front-to-back direction with respect to the front of the apparatus. However, in consideration of mounting optional units such as finishers, ease of use is provided for the user by setting the direction in which paper travels from the paper supply cassette to a lateral direction with respect to the front of the apparatus. Thus, the front of the base printer becomes the right side or the left side in the multi-function machine, and paper restocking and replacements of consumables cartridges such as toner are carried out from the right side (or left side) with respect to the front of the multi-function machine, which is a problem in that operability is inferior. In order to improve operability, it is necessary to ensure that paper restocking and replacements of consumables cartridges such as toner can be carried out from the front of the multi-function machine, that is, from the left side (or right side) of the base printer. This necessitates large-scale change of the drive system and the like.